The 18-year-old has produced assured performances since breaking into the first team in January and showed no stage fright when pitched against Manchester United's Cristiano Ronaldo in Tuesday's goalless draw in the Champions League.
Coach Jose Mourinho has no doubts that the Inter academy product has a glowing future in front of him.
"I think it's right to talk about Santon, who did fantastically in what was his first match in the Champions League," Mourinho told reporters. "We can no longer say he is just a great talent, he is already a great player."
The teenager's pace and tidy work in defence have enabled him to push Brazilian left back Maxwell, a decent player himself, out of the champions' starting line up.
Mourinho has praised Santon's maturity and quiet professionalism, contrasting it with the attitude of fellow academy product Mario Balotelli, the striker who asked to be loaned out because of limited playing time.
"It's easy for a coach to field an 18-year-old player, when the player is a man," he said last month. "Off the field Santon is low profile, the opposite of what he is on it.
"Mario is a good lad, but some people want him to be high profile, and he's not ready to be high profile, even less so off the field."
Inter centre backs Marco Materazzi and Walter Samuel are likely to miss Sunday's game at the San Siro with thigh and calf problems respectively.
Seventh-placed Roma were Inter's main rivals for the title in the last two seasons but a terrible start means their ambitions are limited to securing a Champions League slot this term.
